Unit cooler



Dec. 16, 1941. c. D. MARLO 2,266,373

UNIT COOLER Filed Feb. 17, 1939 2 Sheets-Sheet l C. D. MARLO Dec. 16,1941.

UNIT COOLER Filed Feb. 17, 1959 2 Sheets-Sheet 2 Patented Dec. 16, 1941ourr COOLER Caesar D. Marlo, St. Louis, Mo., asslgnor to Marlo CoilCompany, St. Louis, Mo., a partnership composed of A. T. Marlo, C. D.Mario, and L. C.

Pellegrinl Application February 17, 1939, Serial No. 256,880

4 Claims.

This invention relates to unit coolers, and has special reference tocoolers assembled as unitary portable coolers adapted to be located incooling or refrigerating rooms or compartments for reducing thetemperature therein to as low a degree as desired.

Objects of the invention are to provide an improved cooler constructedand assembled as a unitary device adapted to be placed in a room orcompartment in which the temperature is to be reduced to a low degree,and having means for creating a circulation of cooled or refrigeratedair within the room or compartment; to provide such a device including aportable housing having insulating walls for the refrigerating orcooling and air circulating devices; to provide shutters mounted andarranged to be opened and held opened by the movement of the air throughthe cooler when the air circulating device or blower is in operation; toprovide an improved arrangement of the coils within the housing so as toeliminate short-circuiting of the refrigerant and to insure maximumcapacity of the cooler; to provide an improved defrosting devicearranged in a novel relationship to the coils so as to effect speedydefrosting of the coils without substantially modifying the temperaturewithin the room or compartment in which the unit is located; and toprovide improved means for suspending or supporting the cooler.

Another object of the invention is to provide a cooler for effectingforced circulation of air between series of refrigerating coils, ahousing for enclosing the cooler mechanism as a unit, means fordefrosting the coils speedily and effectively, and shutter devices forclosing the housing during the defrosting operation so as to prevent thewarm air resulting from the defrosting operation from passing from theunit into the room or compartment in which it is mounted.

Other objects of the invention will be readily apparent from thefollowing description, reference being made to the annexed drawings, in

whichv Fig. 1 is a top plan view of my improved unit cooler with part ofthe top wall broken away.

Fig. 2 is an elevation with parts broken away showing that side of thehousing through which the air enters.

Fig. 3 is a horizontal sectional view approximately on the line 33 ofFig. 2.

Fig. 4 is a view showing a portion of one side of the cooler, one of thedetachable panels opposite the ends of the refrigerating coils beingremoved.

Fig. 5 is an elevation showing one end of the cooler.

Fig. 6 is an elevation showing the opposite end of the cooler.

Fig. 7 is an enlarged sectional view approximately on the line 1-1 ofFig. 2.

The housing may be made of any size adapted for its intended use andcomprises side, end, top, and bottom walls including on the insidesheets i of insulating material which are covered on the outside bymetallic sheets 2. One of the vertical walls of the housing is formedwith an opening in which a metallic frame 3 is mounted and retained byfasteners 4. Within the open frame 3, which provides an opening for theflow of air into the housing, an automatically operated shutter,comprising a vertical series of shutter strips 5, is mounted. Theseshutter strips may be made of aluminum, aluminum alloy, or other lightand preferably noncorrodible material, having their upper edges mountedon pivots 6 with the lower edges of the respective strips 5 extendingdownwardly from the upper margins of the adjacent lower strips (Fig. 7).This provides for inward swinging and opening of the shutter whensubjected to the pressure of air circulated through the refrigeratingunit by the forced circulating device,

That wall of the housing directly opposite from the wall containing theframe 3 has a complementary opening in which a frame 1 is mounted. Ashutter device is mounted in the frame 1 and comprises a vertical seriesof strips 8 which may be made of the same material forming the strips 5so as to swing freely on their supporting pivots 8. The upper edges ofthe strips 8 are mounted on the pivots 9 and the lower margins of therespective strips 8 extend downwardly beyond the upper margins of theadjacent lower strips so that, when the strips are in closed position asshown in solid lines (Fig. 7), a complete closure for the outlet of thehousing is provided. The lower margins of the respective strips 8 extendon the outside of the adjacent lower strips so that all of the stripsmay be swung outwardly to open position by the forced current ofcirculating air.

The refrigerating coil core comprises a series of spaced fins l0, and aseries of tubes H extending therethrough and having their ends connectedby return bends I2 and providing a unit adapted to be mounted in theassembly conveniently and without interference with other parts. I 3 isthe inlet of the coils and may be detachably connected with one end ofone of the bottom tubes II. A pressure relief valve l4 of knownconstruction is connected as a by-pass around the outlet valve I 1. Thusshould the pressure in the coil become excessive, the pressure reliefvalve l4 functions to permit the refrigerant to-pass around the valve l1if it is closed. This is especially desirable since heat may be appliedto the coil by the defrosting device and will raise the temperature andpressure of the refrigerant above that usually encountered. Therefrigerating coil may be removed as a unit through the end of thecompartment, provided with a removable panel 18 closing the opening ISin the housing. This panel fits in the opening l9 and is attached to thewall of the housing by nuts 20 screwed on the ends of bolts 2 I.

Two retaining members 22 and 23 are rigidly attached to the inside of apan or tray 24 within the housing, and serve to position the coil. Thepan or tray 24 is attached to the bottom wall of the housing byfasteners 25. The lower ends of the fins 10 are formed with notches 26(Fig. 7), permitting water obtained from defrosting of the tubes 1 l toflow to the drain pipe 21 opening through the bottom of the pan 24. Theends of the retaining members 22 and 23 are separated from the end wallsof the pan 24 by spaces 28 (Fig. 3), also provided to permit water toflow freely to the drain 21.

The coil unit is attached to a pair of rigid frame members 29 by bolts30 engaging parts of the coil unit and having threaded ends extendingthrough the members 29 and provided with nuts 31 whereby the bolts 30may be tightened. The members 29 may be formed with holes 32, permittingfree movement of air therethrough at the ends of the coil unit andpreventing formation of air retaining pockets.

The defrosting device comprises a series of tubes 33 extending throughthe fins l below the coil tubes H. These tubes 33 are preferably ofcopper and, as shown, are of larger diameter than the tubes ll, althoughthe relative dimensions of these tubes may be varied optionally.Electrical heating elements 34 extend through the tubes 33 and may beconnected as shown in series. Electricity is supplied to the heatingelements by circuit wires 35 and 31. When the circuit through the wires31 is closed, the heating elements 34 are heated and, as a consequence,the tubes 33, fins l0, and tubes I l are heated sufficiently to melt thefrost on the tubes and to heat the air within the housing. As aconsequence, the water produced by the melting of the frost on the tubesdrops, or flows along the has It, into the pan or tray 24 andis-discharged through the drain 21. During this defrosting operation,which usually requires only from ten to fifteen minutes, the shuttersand 8 are closed, thereby preventing the warm air from passing fromwithin the housing into the room or compartment in which therefrigerating unit is located. The manner in which the shutter strips 5and 8 are pivotally supported at theirupper edges and leaving the lowerportions thereof extending downwardly, constitutes means forautomatically closing the shutters by gravity when the fan and motor areidle.

The heating tubes are located so that they will heat the coils byconduction, radiation and convection as well as by circulation of therefrigerant within the coils. The position in which aaeasvs they areplaced causes the refrigerant in the coils near the heaters to becomewarm. This. of course, causes a rise in the pressure of the refrigerantin this portion of the coil. The pressure rise causes a movement of therefrigerant away from the heat coils which eflects a circulation of therefrigerant within the coils to aid in the defrosting process. Byutilizing tubes placed in the fins as shown, for encasing the heatingelements, the same machinery used to space and align the refrigeranttubes may be used for fabricating the heating tubes and a veryeconomicalconstruction is achieved. Placing the heating elements beneath therefrigerant tubes and in line therewith increases the emcacy of thedevice. The insulated housing keeps the heat in and the cold out duringa defrosting operation and thus shortens the time required fordefrosting as well as prevents raising of the refrigerator temperature.A switch (not shown) is provided in connection with the wires and 31 toopen and to close the circuit, and it will be understood that saidswitch is kept open when through an opening 42 in the housing wall andinto a box 43 having a removable sliding wall 44. The opposite ends ofthe heating elements 34 extend through an opening 45 in the panel l8 andinto a box 46 having a removable sliding wall 41 which may be removed toafford access to the ends of the heating elements 34 and theirconnections 36, and then replaced as desired.

A frame 48 is attached to the frame 1 and supports a motor 49 within thehousing. A fan 50 is attached to and operated by the shaft 5| of themotor 49 within a circular opening in a frame 52 attached to the frame 1and adjacent to the strips 8. Electric circuit wires 53 furnish powerfor the fan.

When the compressor is operating and the valve I1 is open, refrigerantis forced through the tubes II, and low temperatures can be obtained,ranging from about 32 F. to about 20 below zero, thus adapting thedevice for such low temperature work, as in ice-cream hardening rooms,etc. The device may be suspended by hooks or eyelets 56 attached to thehousing and adapted to engage hangers 51 within the room or compartmentcontaining the device.

When the motor. 49 and fan 50 are operating, a flow of air'through thehousing is caused by suction of the fan 50. The air passes between andacross the tubes ll of the refrigerating coil and is expelled from thehousing through spaces provided by the opening of the shutter strips 8.This suction also opens the shutter strips 5. During this operation, thecircuit through the wires 35 and 31 is open.

When it is desired to defrost the coils, the circuit through the wires53 is opened and the motor 43 and fan 50 are stopped, as a consequenceof which the suction of air into the housing is also stopped. When thesuction of air is stopped, the shutter strips 5 and 8 move to closedposition, and the circuit through the wires 35 and 31 is then closed toheat the heating elements 34 by. which the heating unit is defrosted.The defrosting requires only a com-' paratively short time, usually fromten to fifteen minutes. After the heating unit has been defrosted-thecircuit through the wires 35 and 31 may be manually opened and the motor49 and fan 50 again placed in operation by closing the circuit throughthe wires 53.

It should now be apparent that this invention attains all ofits intendedobjects and purposes in a highly efficient, economical and satisfactorymanner. The construction, arrangement and relationship of the parts maybe varied as widely as the scope of equivalent limits will permitwithout departure from the nature and principle of the invention.

I claim: Y

1. A refrigerating coil comprising a plurality of spaced, parallel,vertical fins, a plurality of spaced, parallel tubes for carryingrefrigerant passing through the fins horizontally and arranged invertical rows, a plurality of tubes beneath said rows passing throughthe fins and provided with electrical heating elements, a shutoff valvein the outlet of said refrigerating coil and a by-pass valve around theshut-off valve arranged to operate at a predetermined temperature orpressure to relieve the pressure in the coil ii the shut-off valve isclosed.

2. A refrigerating coil comprising a plurality of spaced, parallel,vertical fins, a plurality of horizontal tubes that are secured to thefins and arranged to carry refrigerant, said horizontal tubes beingparallel and spaced apart and arranged in vertical rows, a tube for eachof the vertical rows of refrigerant tubes passing through the fins, saidtube being provided with an electrical heating element adapted to beenergized to defrost the coils, said tube and said heating element beingpositioned below and in proximity to the bottom tube of the vertical rowof tubes thereby facilitating rapid defrosting of the coil bysimultaneously heating the inner and the outer surfaces of the frost,said outer surface of the frost being heated directly by the convectionof heat generated by the said heating element, said inner surface of thefrost being heated by circulation of heated refrigerant through thetubes in the vertical row.

3. A cooling unit comprising, an insulated casing, an air inlet in oneof the walls of the casing, an air outlet, shutters closing said inletand outlet and arranged to be opened by a flow of air therethrough, arefrigerating coil positioned upright in the casing, a fan arranged tomove air through the casing and over the refrigerating coil, saidrefrigerating coil consisting of fins and a plurality of tubes forcarrying refrigerant, said tubes being parallel and spaced apart andarranged in vertical rows, and a tube beneath each of said rows passingthrough the fins that is provided with an electrical heating element,said fan being inoperative during the defrosting period therebypermitting the shutters to close and isolate the cooling unit from theatmosphere tobe cooled, said heating element being operative during thedefrosting period and being arranged to facilitate ready defrosting ofthe coil by simultaneously heating the inner and the outer surfaces ofthe frost, said outer surface of the frost being heated directly by theconvection of heat generated by the heating element, said inner surfaceof the frost being heated by circulation of heated refrigerant throughthe tubes in the vertical row.

4. A cooling unit comprising, an insulated casing, an air inlet in oneof the walls of the casing, an air outlet in the opposite wall of saidcasing, shutters closing said inlet and outlet and arranged to be openedby a fiow of air therethrough, a refrigerating coil between the inletand outlet, a fan for moving air through the casing and across therefrigerating coil, said refrigerating coil being provided with fins andtubes passing horizontally therethrough in vertical rows, a tube beneatheach of said rows passing through the fins and provided with anelectrical heating element, a shut-oil valve in the ,outlet of saidrefrigerating coil and a by-pass valve around said shut-off valvearranged to operate at a predetermined pressure or temperature torelieve the pressure within the coil if the shut-oil! valve is closed.

CAESAR D. MARLO.

